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Show Toi V ous Exhalations TH ys; ‘There are fulphurerays aicending into the Air, when the Earth is dry ; there they fer- ment with the nitrous Acids, and fometimes ; generate into Z ler, LightI : till at Jaft it arrives at a certain TH ther, producing an actual Fire and Flame, which with wonderful Swiftnefs fires the whole Train, and fo produces a Flafh and Noife, Thus Dr. Hook. Dr. Wallis, in Philof. Tranfaéé, Ne, 231, That befides the Vapours rais’d from Water, &c. there are alo Exhalations carry’d off from fays, That Thunder and Lightning are fo very wr, Bitun volatile Salts, &c. is patt like the Effe&ts of fir’d Gunpowder, that we all Doubr: ” ntity of fulphureous may reafonably judge they proceed fromthe and bituminous Matterall over the Surface of like Caufes. h, and the volatile Salts of Plants and Nowthe principal Ingredients in Gunpoword fuch an ample Stock thereof, der are Nitre and Sulphur, (the Admiffion of no Wonder the Air fhouldbe fill’d Charcoal being chiefly to keep their Parts {eith fuch Particl raisd higher or lower, parate for the better kindling of it) fo that if cording k : of we fuppofe in the Air a convenient Mixture of AGtivity, and more. copioufly nitrous and fulphureous Vapours, and thofe sread in this or that Quarter, according to by Accident to take Fire, fuch Explofion may the Direction of the Winds, €2c. well follow with Noifé and Light, as in the The. Atmofphere about the Earth abounds firing of Gunpowder ; and being once kindled, ith nitrous Particles of a fpirituous Nature, it will run from Place to Place, as the Vapour hich are every wl carry’d along with it; leads it, like asin a Train of Gunpowder, with s which Sort of Particles, there are others the like Effects sd up into th which may be fomeThis Explofion, if high in the Air, and at of the Nature of fulphurcous, nitrous, far from us, will do no Mifchief, or not conother combuftible Bodies: As we €e Spirit fiderab le, like a Parcel of Gunpowder fired in of Wine, Spirit of Turpentine, Camphire, and the open Air, where nothin is near enoughto g almoft all other combuftible Bodies will by be hurt byit : Butif the Explofion be near to 1 e rarefy’d into the Form of Air or us, or amongift us, it maykill Men or Cattle, Smoak, and be rais‘d up into the Air. tear Trees, fire Gunpowder, break Houies, or Allwhich, if they have a fufficient Degree the like, which Gunpo wder would do in like of Heat, will catch Fire, or be turn’d into Circum ftances, Flame by the nitrous Parts of the Air, as This Nearne or Farne/s maybe eftimated thoufands of Experiments might be brought by the Diftan /s of the Time between feeing ce to prove. the Flash of Lightning, and hearing the Clap ‘There are alfo other Sorts of thefe fulphu- of Thund ; for tho’ in their Genera tion they er Steams which arife from the fubterra- be fimultaneous, yet Light moving fafter than sand mineral Bodies, which only bytheir Sound, they come to us fucceff i ively. ng to mix with the Nitre of the Air, tho’ Lhave obferv'd, that commonlythe Noife they have no fenfible Heat in them, will fo is about feven or eight Seconds after the Flafh; ferment an t one uponanother as to produce an actual Flame, which is a thing that but fometimes ’tis muchfooner in a Secondor has often been found in Mines, and more efpe- two; or lefs than that juft after the Flath ; cially if any Part of them be kindled ; then and then the Explofion muft needs be very near us, and even amongft us: And, in fuch the whole Train, whichis mingled with the contiguous Air, will immediately take Fire Cafes, I have more than once prefaged the Expect ation of Mifchief, and it hath provd like a Train of Gunpowder, and then run from one Endof thofe Vapours to the other, accordingly, Nowthat there is in Lightuing a fulphube they ever fo long ; as I could prove by a reous Vapour, is manifeft from the fulphureous multitude of Relations from Coal Mines, and Smell that attends it, and the fultry Heat in, feveral other Mines. the Air, which is commonly a Fore-runnerof The Afcenfion of which Vapours is fo fud‘ den, and with fuch Violence and Swiftnefs Lightning. And that there isa nitrous Vapour init, we runs from one End to the other, as often to may reafonably judge, becaufe we do not Kill the Miners, blowup their Props, Turns, know of any Body{0 liable to a {udden and Stays, Houfes, &c. and produces as prodiasealu gious Effects, as if a vaft Quantity of Gun- violent Explofion, As to the kindling of thofe Materials, in powder had been fired in the Mine. order to fuch an Explofion, I am told, that Now Lightning in the Air feems to be much of the fame Nature; for the Airis con- Mixture of SulphurandFilings of Steel, a tinually furnifh’d with {pirituous, nitrous Parts, the Admiffion of a little Water, will not only nce, but will of itand the Summer Feat, whenever extraordi- produce a great Efferv felf break forth into an adtual Fire: I nary, raifés up out of the Earth (and to this little Water, becaufe too much will hin the fubterranean Heat alfo is continually concurring) a great Quantity of fulphureous Pneee geote A aywr Vapours, which are of fuch a Nature, as that _Dewesof Hae ane there >y begin a farther g » Which gradually increafes, Operation, or quenchthe Fire. TH Pitch, and then they fall upon, and work uponone ano- Ste 2S: Andthis I take to be the Caufe of the 4 ? Waters, and other hot Springs, w and Sulphur caufe a great Efferveicet no Flame ; fo that there wants only Chalybeate or vitriolick. Vapour (or for equivalent) to produce the whole Effect, (there being no Want of aqueous Matter in the Summer? is hotter; the more commo n fuch Fires are: And this fufficiently fhews, that the Matter offuch Fires is raiied and inflamed by amongf{t the various Efluvia from the Earth, the Heat of the Air and the Impetu ofity of there may be copious Supplies of Matter for its Motion. fuch Mixtures. This may be demonftrated by an Experiment The fame Account may be alfo given of made by the Preparation which Chymi tts call Clouds), and there is no doubt, but that itna, and other burning Mountains, where the Mixture of Iron and Sulphur may give a Flame, whichis often attended with prodigious Explofions and Earthquakes, from great Quan+ tities of Nitre, as in fpringing a Mine. M. Le Clere defines Thunder to be a rumbling Noife in the bigheft Region of the Air, occafioned by the fudden Inflammation of Exhalations. This he explains and accounts for to the Purpofes following : Befides thofe Vapours that are rais’d by the Heat of the Sun, out of the Water and moift there are alfo a world of Particles, re carry’d off from Sulphur, Bitumen, alts, and other Bodies of the like Nature; thefe Particles fly about in the Air, either higher or lower, according to the various ees of their Levity and Gravity ; andthefe are thofe which are by Naturalifts commonly call’d Exhalations, Since it is evident, that there is a vaft Quantity of fulphureous and bituminous Matter all over the Surface of the Earth; and alfo that both Plants and Animals abound with volatile Salts, there is no Caufe that we fhould wonder why the Air is fill’d with fuch Particles by the Heat of the Sun. Nor is it poffible but that they fhould be driven about all over the Air; but it is not to be doubted, but that they arife in greateft Plenty from dry, fun-burnt Places, and hang thereabout; and hence it is eafy to account for all thofe Meteors, which are inflamed in the Air. In all aerial Fires there are three Things obfervable. Aurum fulminans. Gold being diffolved La ‘, the Duft which finks to the Bottom, after it has been dry’d gradually, and withou t Fire, will afterwards be fired by a moderate Heat, andwill go off with a Noife like that of a Musket difcharg’d. This Experiment: may alfo be made at a lefs Expence, and alfo as effectually, by mixing three Dramsof Salt-petre with one Dram of Brimftone, anda Dram and ahalfof Tartar, and beating them toa very fine Powder ; this being done, the Powderwill take Fire as readily as the durum fulminans, but will not give quite fo greata Crack; Nowif it be confider’ds that the Particles of Nitre, Sulphur, and Tartar, which fly in Air, are much finer than thofe of the Com pofition before-mentioned : It is eafy to imagine, that they may befired by a mode Heat aloft in the Air, if they be mixed according to the aforefaid Proportion. This Sort of Matter mutt be carried about the Air in various Figures, accor @ as the Winds blow, and as it is greater or “rin Quantity, and according as it takes Fire. If the Fire begins at one End, and burns gradually, it is called a Lamp; but if a long Exhalation takes Fire at once, it is called a Dart: Sometimes thefe Exhalations are hurried one way or other by the Stream of the Air, while they are in Flame, fometimes they continue in the fame Place, and then theyare called Beams ; at other Times the Clouds part, and the Sky feems to retire, which may be caus’d by the Wind, and a Flame will flath out at this Opening ; when this happens ic is r. That they are lighted without any human Means, andby fomeinvifible Way. 2. That they run about the Air in various call’d a Cha/m. Figures. phur in them (which yields a paler Flame) 3. That fome of them continues longer than others dos but yet they all vanifh in a fhort time. than Nitre, Bitumen, or Tartar, they appear as red as Blood. Though this Sort of Inflammation mayap- In order to makea Flame or Spark appear, there is nothing more neceflary, than that there fhould be fome Particle fo whirl’d about be more plain to befeen in the Night, in the Abfence, of the Sun, the prevalent Light of in the Air, as to caft afide all the groffer Matter, and play about in the moft fubtil Parc ofthe Air. Now, there are fome Matters which are apter to be put in Motion than others 5 fuch as the Parts of Sulphur, Bitumen, Nitre, Se Therefore, when a fufficient Quantity of Matter of thefe Kinds are gotten together, it is no difficult Matter for one or two of thofe Particles to be whirl’d about by the Heat of the Air; and whentheyare once inflamed, to fet Fire to all the reft that are about them; asa Confequence of which it is obfervable, that thefe aerial Fires are common in Summer, but More rare in Winter; and by how muchthe in Aqua Regia, and precipitated with Oil of When burning Exhalations have lefs Sul- pear either by Night or Day, yet they will which obfcures the Sight. Thofe which are commonlycall’d Shooting Stars, are but fmall Exhalations in our Air, and therefore are not properly Stars. [ fack-in-a-Lanthorn, Will-inJ feem to confift of a more greafy Y Exhalation. Itis evident, that oily Subftances, thoughtheyare cafily lighted, yet they are noe fpent fo foon as thofe of Sulphur and Nitre, Hence ic may belearn’d, that all fuchinflamed Exhalations muft neceflarily difappear foon, becaufe the fubtil Matter of which they But as the Matter of confift is foon fpent. hem is notall alike, fo their Continuance is not exactly the fame: We may obferve that 7Z a Flame, |
